The present disclosure relates to a duplex system, and more particularly, to a duplex system that includes a meter measuring a current and voltage.
A duplex system indicates providing and utilizing two components having the same function in order to enhance the reliability of a system. The duplex system includes a spare device for each component so that the entire system does not need to stop when a component in a system abnormally operates. When any one of components in a duplex system has a trouble, the duplex system immediately performs a changeover to a spare device to resume the operation of the duplex system. The duplex system is costly but being widely utilized in a system that needs high reliability and cannot stop its operation.
Such a duplex system is also used in high voltage direct current (HVDC) transmission. The HVDC transmission is one of electricity transmission techniques. The HVDC transmission converts high-voltage alternating current power generated at a power station to highly-efficient high-voltage direct current power by using a power converter into transmit the highly-efficient high-voltage direct current power. According to the HVDC transmission, the direct current power is then re-converted into the alternating current power through the power converter in a desired region. The HVDC transmission is advantageous to long-distance transmission because the amount of power loss is less in comparison to high voltage alternating current transmission.
An HVDC transmission device performing such HVDC transmission uses an inverter converting direct current power into alternating current power and a converter converting the alternating current power into the direct current power. A meter measuring a current and voltage for the control of the inverter and the converter measures the current and voltage at a point of each device of a system and grid to which the HVDC transmission is applied. The HVDC transmission needs high reliability. Thus, the meter measuring the current and voltage includes a duplex system. When the meter normally operates and changes over, there is a risk that there is a shock to the duplex system or the entire system normally operates. Thus, there is a need for a duplex system for preventing the shock or abnormal operation.